<!DOCTYPE html>
<html>

<head lang="en">
    <meta charset="UTF-8">
    <title>正文</title>
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <meta name="renderer" content="webkit">
    <style>
        body {
            margin: 0;
            padding: 0;
        }
        
        .comment {
            background: #f1f1f1;
            width: 100%;
            padding: .4rem;
            border-top: 1px solid #ddd;
            display: flex;
        }
        
        .smile {
            background: url("smile.png") no-repeat;
            background-size: 34px 34px;
            width: 34px;
            height: 34px;
        }
        
        .textarea {
            border: 1px solid #ddd;
            padding: 10px;
            font-size: 38px;
            color: #333333;
            min-height: 34px;
            box-sizing: border-box;
            border-radius: 6px;
            flex: auto;
            margin-left: 16px;
            margin-right: 16px;
        }
    </style>
</head>

<body>
    <div class="comment">
        <div class="smile"></div>
        <textarea class="textarea">添加一条评论</textarea>
    </div>
</body>

</html>